patch 9.0.1981: not being able to scroll up in diff mode

Problem:  Cannot scroll up in diff mode with many filler lines and zero
          'scrolloff'.
Solution: Invalidate w_cline_row before calling comp_botline().

closes: #13256

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: zeertzjq <zeertzjq@outlook.com>
diff --git a/src/version.c b/src/version.c
index d7b3c9b..15e87d6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1981,
+/**/
     1980,
 /**/
     1979,